1. Field of the Invention
The present invention relates to a film comprised of at least one monomolecular layer composed essentially of a polyimide, and a process for its preparation.
2. Description of the Prior Art
Polyimide films have high heat resistance and insulating properties, and have been widely used for electronic materials such as liquid crystal products or semiconductor devices or as permselective membranes such as membranes for enriching hydrogen.
However, most of polyimide films so far prepared had a thickness of about 0.1 .mu.m at the minimum, and the thickness was not necessarily uniform. It is necessary to prepare a thinner and more uniform film to obtain higher performance electronic materials or permselective membranes. However, there has been no practical method for the preparation of a thin film having a thickness of less than about 0.1 .mu.m, whereby it has been difficult to utilize polyimide films on a commercial scale.